1. Field of the Invention
The present invention relates to a pump mechanism for simultaneous delivery of two atomizer liquids to a sprayer device in which the ratio between the two liquids is selectable to a greater degree than possible in the prior art.
2. Description of the Prior Art
In the pump mechanism for simultaneous delivery of two atomizer liquids to a sprayer device of the type known in the prior art, the piston rods of two paint pumps are driven by the see-saw motion of a balance arm. Two air motors in push-pull operation are utilized to impart the see-saw motion about a displaceable support.
The push-pull operation of the air motors requires a clocked reversing of the two air motors, each in a direction opposite to the other. Such clocked reversing of the two air motors is controlled by two pilot valves whose sensors are situated at the two dead points of the maximum piston stroke positions of one of the two air motors. When the piston of the controlling motor mechanically reaches one of the two dead points, the corresponding sensor forwards a pneumatic control signal to the two reversing valves of the two air motors. Consequently, only one of the two motors controls the pneumatic reversing event of both air motors.
The pump mechanisms in the prior art have means for adjusting the ratio of the atomizer liquids delivered to a sprayer device.
A balance arm connects the two piston rods of the air motors. A displaceable support is used as a fulcrum and placed in the region of the balance beam between the two piston rods. The ratio of the quantity of the two liquids used is controlled by moving the displaceable support in the region between the two piston rods thereby increasing the stroke length of one air motor while decreasing the stroke length of the other. However, given that the two pilot valves whose sensors are situated at the two dead points of the maximum piston stroke are located on one motor, the displacement support may only be moved in the region which increases the stroke length of the piston of the controlling motor. As such, the quantity relationship of the two liquid components can be varied to only a limited degree. The quantity of the liquid component that is conveyed by the pump driven by the controlling air motor must always amount to at least 50%. Such a result is disadvantaged in that a greater degree of flexibility in the adjustment of the ratio between the two liquids is desirable.